1. Field of Invention
This invention relates generally to coversheets for such absorptive devices as disposable diapers, sanitary napkins, disposable bed pads, nursing pads, finger dressings, and incontinent briefs, or the like.
2. Prior Art
Usually, absorptive devices consist of a coversheet, an absorbent pad and a barrier sheet in close contact with each other.
Prior art coversheets usually consist of a flexible apertured plastic sheet to prevent liquid absorbed in an absorbent pad, within an absorptive device, from striking through and soiling outer adjacent clothing. The apertured waterproof plastic sheet of the prior art does provide some degree of dryness. In order for an absorptive device to be acceptable to the public, specifically women, liquid excreted by the body must be capable of being transferred through the coversheet, which is in intimate contact with the body, away from the body into an absorbent pad as quickly as possible. Thus, this quick transmittal of liquid through a coversheet is an essential requirement in developing an absorptive device. In addition, the prior art plastic sheets do not adhere or come into intimate contact with an absorbent pad. Thus, this may result in the absorbent pad shifting within the device thereby causing problems. Additionally the prior art plastic sheet material has an undesirable touch and it sticks to the skin of the user. The present invention has a textile-like surface which results in excellent comfort when in contact with the skin.
In U.S. Pat. No. 3,881,489, there is provided a disposable absorptive device having an absorptive body enclosed within a top coversheet and an improved breathable liquid impervious backsheet. The topsheet may be any conventional top sheet, such as described in U.S. Pat. Reissue No. 26,151. The improved backsheet comprises the combination of two distinct adjacent hydrophobic layers to form an effective breathing portion of the backsheet. The first layer being liquid permeable and having a low void volume while the second layer is liquid permeable and having a higher void volume than the first. The combination of the two backsheet layers prevent the passage of liquid while permitting the passage of gase therethrough. A disadvantage associated with the aforementioned prior art is that the topsheet is a typical topsheet made from a plastic film without any distinguishing features, such as dryness or fluid penetration.
In U.S. Pat. No. 3,292,619, there is described an invention directed to a non-adherent dressing in which only portions of the surface of the body side thereof are in contact with the body when applied to cover a wound therein. Only a minor portion of the total surface area of the body side of the dressing is in contact with the body. The major sites of fluid intake into the absorbent pad, in accordance with that invention, are located in depressions in the surface of the dressing which is in contact with the body. The walls of the depression are sloped inwardly into the body of the dressing and are lined with a thin film which covers the surface of the pad at the body side of the dressing. The film lining the walls of the depressions is perforated. Each depressed film portion containing a plurality of openings into which the fluid passes. A disadvantage of this prior art fabric is that it is bonded together by passing it between the nip of an embossed roll and a smooth surface roll which imparts depressions to the fabric. The depressions in the fabric thus reduce the total area that is available in the absorbent material for absorbing fluid.
In U.S. Pat. No. 3,331,728, there is described a film-fiber laminate that is made as a coversheet to cover absorbent material, such as that used in a sanitary napkin. The laminate is made in a continuous process with the film, as formed by a film extruder, being laid immediately onto an underlying perforated fiber web. Suction is then applied to the underside of the perforated web, with the freshly extruded film still in the highly tacky fluid state, to secure intimate bonding between the film and the underlying fibrous web, while at the same time rupturing the film in the areas immediately overlaying the openings in the fiber web, causing openings to be completely through the fabric. A disadvantage of the aforementioned prior art is that the openings in the composite are through the film and the fibrous web. This allows for ingress of fluid to pass through the composite into an absorbent material, but also allows for egress of the fluid, thus presenting a problem in containing fluid in a product, such as a sanitary napkin.
The aforementioned disadvantages in the prior art are not present in this invention because it is an integral composite made in one process step, having no depressions and no holes through the fibrous web. In addition to it being more economical to produce, it has qualities that are not present in the prior art which will be more evident in the remainder of this specification, drawings and claims.
An object of this invention is to provide a substrate having excellent tensile strengths, fluid penetration rewet properties, and textile-like surfaces.
Another object of this invention is to provide a coversheet having minimal fluid retention capacity.
Still another object of this invention is to provide a coversheet that has a fibrous surface on one side that will contact the wearer skin to give comfort and on the opposite side a fibrous surface that has sufficient roughness to stay in intimate contact with an absorbent material adjacent thereto.